This invention relates to an intraocular lens for use as an artificial lens implant after surgical removal of a cataracted human lens from an eye. More particularly, to an intraocular lens which may be inserted through an incision much smaller than that ordinarily required for insertion of known intraocular lenses of this type.
Heretofore, there have been known intraocular lenses of many types, generally having a medial light-focusing lens body for focusing light on the retina of the eye and a pair of haptics extending from opposite peripheral regions of the lens body for seating the lens in the eye in proper relation to the pupil. The lens body is typically of such material and of such configuration that it exhibits the proper optical characteristics for focusing light on the retina of the eye in which it is to be seated. The known intraocular lenses are made of materials such as, for example, polymethylmethacrilate (PMMA) which are inert with respect to the fluids and tissue within the eye and are inserted into the eye through an incision which is typically at least as large as the smallest diameter of the lens body, or optic, of the lens in question.
Recently, several attempts have been made to develop lenses whose lens bodies are deformable so that they may be inserted through a smaller incision than that previously required. One such known lens has both its optic and haptic portions made of Hema. The known Hema lens has the general shape of the Choyce lens, i.e. a generally rectangular, flat, lens, having a central optic portion and flat sheet-like haptic portions extending from opposite peripheral regions of the optic portion. The lens (i.e. both the optic and the haptic) is fabricated with the Hema material in dry, i.e. dehydrated, and thus contracted condition. The dehydrated lens can be readily inserted through a small incision in the eye. Thereafter, the Hema material slowly absorbs the fluid in the eye and slowly expands to its desired shape. The grave disadvantage of such lenses is that the haptics, since they are also formed of Hema, are also in contracted, i.e. dehydrated, condition at the time of insertion and it takes a considerable amount of time for the haptics to return to their desired expanded shape and size. Such haptics, cannot be properly seated until they are back in expanded condition. The eye incision, therefore, cannot be closed until the haptics have returned to their original expanded shape and are known to be properly seated. The prolongation of the surgical procedure necessitated by such known Hema lens construction inevitably increases the risk of complication.
Another known intraocular lens of Hema is the one disclosed in U.S. Pat. No. 4,449,257 issued May 22, 1984. The latter patent teaches a Hema lens which is shaped specifically for implantation and retention in the posterior capsule and held in place therein by concentric grooves cut in the marginal peripheral portion of the lens. While the Hema optic may, according to this latter patent, be inserted into the eye through a relatively small incision, several disadvantages are believed to result. First, in order to be certain of proper seating of the lens (which has no haptics extending therefrom) it would appear that the incision must be kept open until the Hema optic has expanded to substantially its final enlarged condition, since it is only then that such lens may be properly seated. Secondly, the lens in question can only be used in the posterior capsule and cannot be seated in any other portion of the posterior or anterior chamber. Thirdly, the Hema optic according to U.S. Pat. No. 4,449,257 can only be used in an eye in which the posterior capsule is in reasonably good condition and sufficient portions thereof remain in tact for retaining the optic in place. Lastly, the Hema optic according to the latter patent must be sized such that it will fill the particular posterior capsule of the patient in question, since if it expands to too large a size it may damage the posterior capsule, while on the other hand, if its expanded size is too small, it may not seat properly.
It would, of course, be highly advantageous to be able to reduce not only the size of the incision but also to reduce the length of time required for performing the surgical procedure. By doing so the patient's recovery would be speeded and the possibility of complications resulting from the surgery would be minimized.